Abstract: Modified starch ester-urethanes prepared by reacting a starch ester containing residual hydroxyl groups with an ethylenically unsaturated isocyanate. The grafted starch ester is a urethane-containing product having pendent groups such as alphamethylstyrene and/or methacrylate moieties. The starch ester-urethane is capable of undergoing crosslinking reactions on exposure to ultraviolet radiation in the presence of a photoinitiator, and optionally ethylenically unsaturated monomers or oligomers. The ethylenically unsaturated starch ester-urethanes of this invention are useful for protective coatings for wood, metal, and plastics.